Broken garage door spring. Garage door spring usually less 7-15 years, It's depends on the quality of the springs and also by cycles.
When one spring brake, We always recommend to replace them both. It's just not worth to deal with it again a few months later, plus it will be more expensive to do it twice.
While replacing the spring some more adjustments need to be done like the cables on the sides and the garage door opener.
Keep in mind, Replacing garage door spring is very dangerous and if you don't know exactly what you doing, you may finish your day at the emergency room. Sometimes It's better to spend more time and watch a few videos on YOUTUBE and see the exact steps, Or just pay someone like us to replace it for you :)